Is it likely that Ultra High Energy Cosmic Rays (UHECRs) like the OMG particle come from alien spacecraft propulsion systems?
I realize this is a bit "out there", but my reasoning behind it is that ...

13 billion years ago, the universe was about 600 million years old according to many scientists. At that time, all matter in the universe would have to be closer, or in other words denser.
Did time ...